Answer: character
Step-by-step explanation:
From the question, we are informed that Karl knows that TrueHeart Industries prides itself on using green processes to reduce its impact on the environment and that during his interview with the hiring manager at TrueHeart, Karl recounted a story about the recycling program he set up in his dormitory at the university.
By doing so, Karl was communicating to his potential employer that he has character. Doing this will help leave a positive impression on the hiring manager.